Molecule thought to be absent in vertebrates found in fish

The long-held belief that vertebrates do not produce a molecule common in insects has been overturned, suggesting that insect pesticides targeting the molecule could also affect these animals.

Scientists have found that the molecule chitin, a primary structural chemical in an insect's body wall, is also found in some vertebrates. Vertebrates are a class of animals with a backbone or spinal column, which includes amphibians and fish.

Assistant Professor Javier Fernandez of the Singapore University of Technology and Design, an author of the study, said it had been assumed that vertebrates do not produce chitin.

"Since they don't contain chitin, the assumption was that they will not be affected by such pesticides at all. But what we have demonstrated is that that assumption is wrong," said Prof Fernandez.

He and colleagues from Harvard University, the University of Washington in Seattle and the Benaroya Research Institute, also in Seattle, found the presence of a gene called chitin synthase, whose activity is necessary to produce chitin, in several types of fish and amphibians, including zebrafish and salamander.

Further experiments found that the genes were not dormant, but expressed the chitin molecules.

A carbohydrate extracted from the scales of salmon exhibited all the chemical hallmarks of chitin, he said.

The scientists also discovered that the chitin synthase gene is important to the development of fish, by carrying out an experiment where the gene was removed from zebrafish larvae.

"When we did this, the embryos of the fish became unstable, developed deformities and were not able to grow, and died before they became mature fish," he said.

Associate Professor Federico Lauro of the Asian School of the Environment at Nanyang Technological University said that while the results indicate chitin probably plays a role in some vertebrates, this did not apply to all of them.

He said a lot needs to be done before one can say that chitin plays a major role in what such animals do. "But it is certainty significant as chitin was previously thought to have nothing to do with vertebrates. That is really interesting."

A version of this article appeared in the print edition of The Straits Times on September 30, 2016, with the headline 'Molecule thought to be absent in vertebrates found in fish'. Subscribe